DevOps for Developers
(2012)

ed descriptions of machines by using a DSL while enjoying the full power of scripting languages (in both Puppet and Chef, you can describe behavior in the Ruby language (a dynamic, general-purpose object-oriented programming language), see http://www.ruby-lang. org/en/). Declarative descriptions of target behavior (i.e., what the system must be). Thus, running the scripts will always lead to the same end result. Management of code in version control. By using a version control system as the leading medium, you do not need to adjust the machines manually (which is not reproducible). Synchronization of environments by using a version control system and automatic provisioning of environments. Continuous integration servers, such as Jenkins, simply have to listen to the path in the version control system to detect changes. Then the configuration management tool (e.g., Puppet) ensures that the corresponding machines apply the behavior that is described in version control. Using tools such as Jenkins (see Chapter 8) and Puppet and Vagrant (see Chapter 9), complete setups, including virtualizations, can be managed automatically. Sharing of scripts (e.g., Puppet manifests). A cross-functional team that includes development and operations can develop this function. Sharing the scripts in the version control system enables all parties, particularly development and operations, to use those scripts to set up their respective environments: test environments (used by development) and production environments (managed by operations). Automation is an essential backbone of DevOps (see Chapter 3 and Chapter 8 for more information on automation). Automation is the use of solutions to reduce the need for human work. Automation can ensure that the software is built the same way each time, that the team sees every change made to the software, and that the software is tested and reviewed in the same way every day so that no defects slip through or are introduced through human error. In software development projects, a high level of automation is a prerequisite for quickly delivering the best quality and for obtaining feedback from stakeholders early and often. Automating aspects of DevOps helps to make parts of the process transparent for the whole team and also helps deploy software to different target environments in the same way. You can best improve what you measure; and to measure something usefully, you need a process that delivers results in a reproducible way. DevOps addresses aspects similar to those tackled by Agile development, but the former focuses on breaking down the walls between developers and operations workers. The challenge is to communicate the benefits of DevOps to both development and operations teams. Both groups may be reluctant to start implementing the shift toward DevOps because their day is already full of activities. So why should they be concerned with the work of others? Why should DEVOPS FOR DEVELOPERS 31 operations want to use unfamiliar tools and adjust their daily routines when their self-made, isolated solutions have worked just fine for years? Because of this resistance, the incentives and commitment provided by upper management are important. Incentives alone are not enough: unified processes and tool chains are also important. Upper management will also resist by questioning the wisdom of implementing DevOps if the concrete benefits are not visible. Better cash flow and improved time to market are hard to measure. Management asks questions that address the core problems of software engineering while ignoring the symptoms: how can the company achieve maximal earnings in a short period of time? How can requirements be made stable and delivered to customers quickly? These results and visions should be measured with metrics that are shared by development and operations. Existing metrics can be further used or replaced by metrics that accurately express business value. One example of an end-to-end metric is the cycle time, which we will discuss in detail in Chapter 3.